1. Field of the Invention
The present invention relates to an image pickup device such as a digital camera. More specifically, the invention relates to an image pickup device with a brightness correcting function of correcting the brightness of an image and a method of correcting the brightness of an image used in the image pickup device.
2. Description of the Related Art
A digital camera includes a strobe light for compensating for a shortage of luminous energy during picture taking. Since, however, the range of flashes of the strobe light is relatively short, the strobe light may not emit an adequate amount of light when a picture of distant scenery or a picture of wide range is taken.
As a digital camera has recently decreased in size, a strobe light loaded into the camera has tended to do so. Not only the small strobe light emits a small amount of light, but also the camera decreases in sensitivity due to the downsizing of cells of image pickup elements. These factors cause a shortage of luminous energy even though a strobe light is used and thus often make it impossible to form an image with desired brightness.
Conventionally, exposure is controlled during picture taking as a method of correcting the brightness of an image. For example, the following technology is known. An aperture/shutter mechanism is so controlled that an amount of exposure made when the maximum Y signal (luminous signal) becomes about 70% to 100% of a dynamic range of CCD. Exposure can thus be optimized to take a picture of a bright subject brightly and take a picture of a dark subject darkly.
However, the above method is merely a correction of exposure, and the brightness of an image is simply adjusted using the aperture/shutter mechanism at the state of exposure before picture taking. It is therefore impossible to correct the brightness of an image of a taken image, such as an image of a subject at which no flashes arrive from a strobe light while the subject is being photographed.
There is a method of correcting the brightness of a taken image using specific software incorporated into a personal computer or the like. In this method, however, a user has to capture the image into the computer, confirm the brightness of the taken image on the screen of the computer and adjust it finely through a predetermined operation. That is, the user has to perform very complicated operations.